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669 results

    • Seminar

    • Cryptography

    Décodage des codes de Reed-Solomon et logarithme discret dans

    • March 21, 2014

    • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

    Speaker : Daniel Augot - INRIA Saclay

    Alors que le problème associé au décodage des Reed-Solomon est connu pour être NP-complet, on sait pas bien quelles sont les instances difficiles, ni si les codes de Reed-Solomon standard font partie de ce ces instances.<br/> Dans le but d'analyser les codes standard, Cheng et Wan étudient depuis 2004 comment le logarithme discret sur les corps non premiers se réduit à un certain problème de[…]
    • Seminar

    • Cryptography

    Bad reduction of genus 3 curves with complex multiplication

    • October 17, 2014

    • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

    Speaker : Garcia Lorenzo - Université de Catalogne

    Let C be a smooth, absolutely irreducible genus 3 curve over a number field M. Suppose that the Jacobian of C has complex multiplication by a sextic CM-field K. Suppose further that K contains no imaginary quadratic subfield. We give a bound on the primes P of M such that the stable reduction of C at P contains three irreducible components of genus 1.
    • Seminar

    • Cryptography

    Is there an L(1/4) algorithm for the discrete logarithm problem in algebraic curves?

    • March 27, 2015

    • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

    Speaker : Maike Massierer - LORIA

    The function field sieve, an algorithm of subexponential complexity L(1/3) that computes discrete logarithms in finite fields, has recently been improved to an L(1/4) algorithm, and subsequently to a quasi-polynomial time algorithm. Since index calculus algorithms for computing discrete logarithms in Jacobians of algebraic curves are based on very similar concepts and results, the natural question[…]
    • Seminar

    • Cryptography

    Decoding interleaved Gabidulin codes and skew complexity of sequences.

    • May 23, 2014

    • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

    Speaker : Vladimir Sidorenko - Univ. Ulm

    Gabidulin codes are the rank metric analogues of Reed?Solomon codes and have found many applications including network coding and cryptography. Interleaving or the direct sum of Gabidulin codes allows both decreasing the redundancy and increasing the error correcting capability for network coding. We consider a transform domain algorithm correcting both errors and erasures with interleaved[…]
    • Seminar

    • Cryptography

    SCREAM/iSCREAM: Side-Channel Resistant Authenticated Encryption with

    • November 14, 2014

    • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

    Speaker : François-Xavier Standaert - Université Catholique de Louvain

    In this talk, I will describe the family of authenticated encryption (with associated data) algorithms SCREAM and iSCREAM. They are based on Liskov et al.'s Tweakable Authenticated Encryption (TAE) mode with the new tweakable block ciphers Scream and iScream. The main desirable features of SCREAM and iSCREAM are:<br/> * A simple and regular design allowing excellent performances on a wide range of[…]
    • Seminar

    • Cryptography

    How to find low-weight polynomial multiples.

    • June 13, 2014

    • IRMAR - Université de Rennes - Campus Beaulieu Bat. 22, RDC, Rennes - Amphi Lebesgue

    Speaker : Carl Löndahl - Université de Lund

    We present an improved algorithm for finding low-weight multiples of polynomials over the binary field using coding heoretic methods. The associated code defined by the given olynomial has a cyclic structure, allowing an algorithm to earch for shifts of the sought minimum-weight odeword. Therefore, a code with higher dimension is onstructed, having a larger number of low-weight codewords nd[…]